We follow Ropiquet and Hassanin (2005) in removing this species from the genus Hemitragus, and placing it in the monotypic genus Nilgiritragus, based on analyses of four molecular markers. No subspecies are recognized.

Justification:
Listed as Endangered because its population size is estimated to number fewer than 2,500 mature individuals, there is an observed continuing decline in the number of mature individuals, and no subpopulation contains more than 250 mature individuals.

The present distribution of the Nilgiri tahr is limited to approximately 5% of the Western Ghats in southern India, in Kerala and Tamil Nadu in southern India (Shackleton, 1997; Grubb, 2005), although not along the border between these two states (M. Alembath pers. comm. 2007). At the beginning of this century the range of tahr probably extended northward at least to the Brahmagiri hills of southern Karnataka (Shackleton, 1997). The animals are more or less confined to altitudes of 1,200 to 2,600 meters (Nilgiri Tahr Trust); populations as low as 900 m may or may not represent pre-human extent of occurrence in elevation (Rice, 1984).

Total numbers were estimated at between 2,000 and 2,500 individuals in the 1970s-1980s, and were thought to be stable (Davidar, 1978; Rice, 1988a, 1990). More recently Daniels et al. (2008) estimated the total population at no more than 1,800-2,000 individuals. An overall decline in the species was suggested by Daniels et al. (2008), although some populations appear to have remained stable in recent decades (Mishra and Johnsingh 1998). The species current populations are estimated to be Nilgiri hills (450, though now reduced to 75-100), Silent Valley (30), Siruveni Hills (20), Elival Mala (60), Nelliampathi Hills (30), Top Slip and Parambikulam (120), Eastern Slopes of Ananmala (125), Grass Hills of Anamala (250), Swamaimala (130) Eravikulam National Park (760), High Range (30), Palani Hills (60), Highwavy mountains (100), Mudaliar oothu (70), Vellakaltheri (90), Ashambu Hills (70), and Thiruvannamalai peak (40) (Nilgiri Tahr Trust, retrieved 02 January 2007).

The Nilgiri tahr is found at high elevations on cliffs, grass-covered hills, and open terrain (Nilgiri Tahr Trust, retrieved 03 January 2007). Females gestate for about 180 days, and usually give birth to one kid per pregnancy (Rice, 1984). Animals are sexually mature in the wild at around three years of age (Wilson, 1980; Rice, 1990), though they are only expected to live three or 3.5 years on average, their potential life span is at least 9 years (Rice, 1988; Rice, 1990). The species is diurnal, but are most active grazing in the early morning and late afternoon (Prater, 1971; Nowak, 1991).

Principal threats are habitat loss (mainly from domestic livestock and spread of invasive plants) and poaching (Daniels et al. 2008). The general trends of decline even in the best managed Tahr habitats indicate that the total population of the species does not exceed 2000 at present and a conservative estimate would place the numbers within the 1,800-2,000 range (Daniels et al., 2006). Currently, the only populations with more than 300 individuals are in Eravikulam National Park and in the Grass Hills in Anamalai. The most recent information from the Nilgiri hills (Mukurti Wildlife Sanctuary), which previously had more than 300 tahr (Davidar, 1978; Rice, 1984; Schaller, 1971), indicates that only between 75 and 100 individuals remain. Wattle (Acacia mearnsii) plantations and cattle apparently no longer threaten the Mukurti population, so their decline is probably due solely to illegal hunting. The status of the other smaller populations (many of which are less than 100 individuals), which are also subject to continued illegal hunting, can be considered precarious. Similar population decreases and threats to the species were reported in a survey in Kalakad-Mundanthurai Tiger Reserve (Rai and Johnsingh, 1992).

Populations of these animals are small and isolated, making them vulnerable to local extinction. Habitat patches for Nilgiri tahr are naturally discontinuous, but some habitat fragmentation may have anthropogenic causes (C. Rice pers. comm., 2008). The species faces competition from domestic livestock, whose overgrazing has allowed for the invasion of graze-resistant weedy species into preferred meadows, thus in competition with the native grasses that tahr prefers (Mishra and Johnsingh, 1998). Continued conversion of tahr habitat to agricultural land has resulted in a present distribution that is about one-tenth of its historical range (Mishra and Johnsingh, 1998; Kannery, 2002; IUCN, 2004).

The Nilgiri tahr is fully protected (Schedule I) by the Indian Wildlife (Protection) Act of 1972, although this protection is rarely enforced and illegal hunting is a major threat (Kannery, 2002; IUCN, 2004).

The creation of Eravikulam and Silent Valley National Parks, Mukurti, Anamalai, and Parambikulam Wildlife Sanctuaries, and Srivilliputhur Grizzled Giant Squirrel Sanctuary and the Kalakadu-Mundanthurai Tiger Reserve, together offer an important degree of protection to the Nilgiri Tahr. Eravikulam National Park and its surroundings has been cited as having nearly 1,000 individuals (Kannery, 2002), although others have questioned this figure, believing it to be too high (Abraham et al. 2006, M. Alembath pers. comm., 2008).

The Tamil Nadu Forest Department is removing exotic monocultures along the periphery of the Mukurti National Park. In addition, institutions such as the Nilgiri Wildlife Association, High Range Wildlife Association, Ramnad District Wildlife Association, Kerala Forest Research Institute, Bombay Natural History Society and the Wildlife Institute of India, are active in promoting conservation of Nilgiri tahr. Conservation measures proposed: The Nilgiri tahr requires continuous study and monitoring, because its small and isolated populations are extremely vulnerable. With proper conservation, including habitat maintenance and minimising mortality due to hunting, it is possible that with time, the species could be considered no longer threatened, if the following are accomplished: 1) Establish the proposed Nilgiri Biosphere Reserve. This would include the Bandipur, Nagarhole and Silent Valley National Parks, the Mudumalai, Mukurti and Wynad Wildlife Sanctuaries, the Bolampatti Reserved Forest and the proposed Karipuzha National Park (WCMC, 1988c), and encompass a Nilgiri tahr population of 400 to 450 individuals (Davidar, 1978; Rice, 1984). An extension to such a reserve has also been proposed (Rice, 1990) to include peripheral cliffs used by tahr as escape and birthing terrain. A revised biosphere reserve design of these conservation units has been suggested by Rodgers and Panwar (1988). 2) Enact management proposals that include the systematic monitoring of tahr populations, as well as possible re-introductions (Rice, 1988a, 1990; Rai and Johnsingh, 1992). There is good potential for re-introductions in areas such as the Kalakadu-Mundanthurai Tiger Reserve where several highlands had small populations of tahr some 20 to 40 years ago, but today are very small or non-existent (Rai and Johnsingh, 1992). 3) Consider low impact recreational use (e.g. trekking, fishing) of suitable areas, especially where such activities would benefit (and compensate) the local economy for restrictions on traditional activities such as hunting by local inhabitants. 4) Co-ordinate Nilgiri tahr with other wildlife and habitat conservation efforts, because the Western Ghats are one of India’s major wildlife areas.